var tm;
var imageCount = 0;
var imageArray = ['images/ban_1.png','images/ban_2.png', 'images/ban_3.png', 'images/ban_4.png', 'images/ban_5.png', 'images/ban_6.png', 'images/ban_7.png', 'images/ban_8.png', 'images/ban_9.png', 'images/ban_10.png', 'images/ban_11.png']
function next() {
if (imageCount!=imageArray.length-1) imageCount++
else imageCount = 0;
document.images['ban'].src=imageArray[imageCount];
}